Recording material for color photography

ABSTRACT

Compounds of the formula I   &lt;IMAGE&gt;   in which A, R1, R2, R3, R4, R5 and R6 are as defined in claim 1, are effective optical stabilizers for photographic dyes and their precursors. They are added to the colorphotographic recording materials as the latter are being prepared, and, as a result, the developed images have a longer optical stability.

The present invention relates to a recording material for colourphotography, which contains a specific polyalkylpiperidine compound as astabiliser in at least one light-sensitive silver halide emulsion layerand/or in at least one of the customary auxiliary layers.

As sterically hindered amines, polyalkylpiperidines are generally knownfor use as optical stabilisers for organic materials, in particular forpolymers. German Offenlegungsschrift No. 2,126,954 already proposesusing such polyalkylpiperidines as agents against the fading of colourphotographs. European Pat. No. A 11,051 further proposes using, asoptical stabilisers for colour photographs, certain polyalkylpiperidinederivatives which contain at least one phenol group. Thesepolyalkylpiperidine derivatives are polyalkylpiperidine esters ofhydroxybenzylmalonic acids.

In continuance of this research work, it has been found that amides ofphenolalkanecarboxylic acids and 4-aminopolyalkylpiperidines likewisehave an excellent optical stabilising action for colour photographs and,moreover, also effect in the dark a stabilisation of the dyes to changesduring storage of the recording material.

Accordingly, the present invention relates to a recording material forcolour photography which, in at least one light-sensitive silver halideemulsion layer, an intermediate layer, an image-receiving layer and/or aprotective layer, contains, as stabiliser, at least onepolyalkylpiperidine compound of the formula I ##STR2## in which R¹ ishydrogen or methyl, R² is hydroxyl, C₁ -C₁₂ -alkyl, C₃ -C₆ -alkenyl, C₃-C₄ -alkynyl, C₇ -C₁₂ -aralkyl, gycidyl, C₁ -C₄ -alkyl which issubstituted by halogen, cyano, --COOR⁷ or --CON(R⁸)(R⁹), or a --CO--R¹⁰,--CO--OR⁷, --CO--N-- (R⁸)(R⁹), --CH₂ --CH(R¹¹)--OR¹², --SO--R¹³, --SO₂--R¹³, --OR⁷ or --OOC--R¹⁰ group, R³ is hydrogen or methyl, R⁴ is C₁ -C₈-alkyl, C₅ -C₈ -cycloalkyl, C₇ -C₉ -phenylalkyl, phenyl or C₇ -C₁₀-alkylphenyl, R⁵ is hydrogen, C₁ -C₈ -alkyl, C₅ -C₈ -cycloalkyl, C₇ -C₉-phenylalkyl, phenyl or C₇ -C₁₀ -alkylphenyl, R⁶ is hydrogen, C₁ -C₁₈-alkyl, C₃ - C₆ -alkenyl, C₃ -C₁₂ -cycloalkyl, C₇ -C₁₂ -aralkyl, C₇ -C₁₀-alkylphenyl or C₂ -C₄ -alkyl which is substituted by --OR⁸, --N(R⁹)₂ ora group of the formula ##STR3## R⁷ is C₁ -C₁₂ -alkyl, allyl, cyclohexylor benzyl, R⁸ is C₁ -C₁₂ -alkyl, allyl, cyclohexyl, benzyl or phenyl, R⁹is hydrogen, C₁ -C₁₂ -alkyl, allyl, cyclohexyl or benzyl, or R⁸ and R⁹,together with the N atom to which they are bonded, are a 5- or6-membered heterocyclic ring, R¹⁰ is hydrogen, C₁ -C₁₂ -alkyl, C₂ -C₆-alkenyl, chloromethyl, C₅ -C₈ -cycloalkyl, C₇ -C₁₂ -aralkyl, phenyl, C₇-C₁₀ -alkylphenyl or phenyl, phenylmethyl or phenylethyl which aresubstituted by 1 or 2 C₁ -C₄ -alkyl groups and a hydroxyl group, R¹¹ ishydrogen, C₁ -C₄ -alkyl, C₂ -C₁₃ -alkoxymethyl, phenyl or phenoxymethyl,R¹² is hydrogen, C₁ -C₁₂ -alkyl, --CO--R¹⁰ or --CO--N(R⁸)(R⁹), R¹³ is C₁-C₁₂ -alkyl, phenyl or C₇ -C₁₈ -alkylaryl, A is hydrogen, C₁ -C₁₈-alkyl, C₁ -C₁₀ -alkyl which is substituted by at least one of the--OR¹⁴, --SR¹⁵, --CN, --CO--X--R¹⁶, --O--CO--R¹⁷ or --P(O)(OR¹⁸)₂groups, C₂ -C₂₀ -alkyl which is interrupted by --O--, --S--, --SO-- or--SO₂ --, C₃ -C₁₈ -alkenyl, C₃ -C₈ -alkenyl, C₃ -C₁₂ -cycloalkyl, C₆-C₁₀ -alkylcycloalkyl, C₆ -C₁₀ -cycloalkylalkyl, C₇ -C₁₂ -aralkyl, C₈-C₁₆ -alkylaralkyl, phenyl, a --CN, --CO-- R²⁰, --CO₂ --R²¹ or--P(O)(OR¹⁸) group or one of the following groups ##STR4## in which X is--O-- or --N(R¹⁹)--, R¹⁴ is phenyl, benzyl or cyclohexyl, R¹⁵ is phenylor C₇ -C₉ -phenylalkyl, R¹⁶ is C₁ -C₁₈ -alkyl, C₅ -C₈ -cycloalkyl andR¹⁷ is C₁ -C₁₈ -alkyl, C₅ -C₈ -cycloalkyl, phenyl, C₇ -C₉ -phenylalkylor a group of the formula ##STR5## R¹⁸ is C₁ -C₈ -alkyl, allyl orphenyl, R¹⁹ is hydrogen, C₁ -C₁₈ -alkyl, allyl, cyclohexyl, benzyl orphenyl or, together with R¹⁶ and the N atom, a 5- or 6-memberedheterocyclic ring, R²⁰ is hydrogen, C₁ -C₁₈ -alkyl, C₂ -C₆ -alkenyl, C₅-C₈ -cycloalkyl, phenyl, C₇ -C₁₀ -alkylphenyl or C₇ -C₉ -phenylalkyl,R¹² is C₁ -C₁₈ -alkyl, cyclohexyl, phenyl, naphthyl, C₇ -C₁₈ -alkylaryl,C₇ -C₉ -phenylalkyl or a group of the formula ##STR6## m is zero, 1 or2, and n is zero, 1, 2 or 3.

In the formula I, R⁴, R⁵ and R¹⁸ can be C₁ -C₈ -alkyl, and as such theycan be unbranched or branched alkyl, for example, methyl, ethyl, propyl,isopropyl, butyl, tert.-butyl, isoamyl, n-hexyl, 2-ethylbutyl, n-octylor 1,1,3,3-tetramethylbutyl. C₁ -C₁₂ -alkyl radicals R², R⁷, R⁸, R⁹,R¹⁰, R¹² and R¹³ can also be for example nonyl, decyl or dodecyl. C₁-C₁₈ -alkyl radicals R⁶, R¹⁶, R¹⁷, R¹⁹, R²⁰, R²¹ and A can moreover alsobe, for example, tetradecyl, hexadecyl or octadecyl.

C₃ -C₆ -alkenyl radicals R² and R⁶ can be, for example, allyl,methallyl, 3,3-dimethylallyl or 2-butenyl. C₂ -C₆ -alkenyl radicals R¹⁰and R²⁰ can also be vinyl or isopropenyl. A C₃ -C₁₈ -alkenyl radical Acan be defined in the same way as R² and, moreover, be, for example,2-octenyl, 11-undecenyl or oleyl.

A C₃ -C₄ -alkynyl radical R² can be, for example, 2-propinyl or butinyl.A C₃ -C₈ -alkynyl radical A can moreover also be, for example, 2-hexynylor 2-octynyl.

C₅ -C₈ -cycloalkyl radicals R⁴, R⁵, R¹⁰, R¹⁶, R¹⁷ and R²⁰ can be, forexample, cyclopentyl, cyclohexyl or cyclooctyl. C₃ -C₁₂ -cycloalkylradicals R⁶ and A can moreover also be cyclopropyl, cyclobutyl,cyclodecyl or cyclododecyl.

A C₆ -C₁₀ -alkylcycloalkyl radical A can be, for example,methylcyclopentyl, monomethylcyclohexyl, dimethylcyclohexyl,monomethylcyclooctyl or dimethylcyclooctyl. A C₆ -C₁₀ -cycloalkylalkylradical A can be, for example, cyclopentylmethyl, cyclohexylmethyl,cyclohexylethyl or cyclooctylmethyl.

C₇ -C₉ -phenylalkyl radicals R⁴, R⁵, R¹⁵, R¹⁷, R²⁰ and R²¹ can be, forexample, benzyl, 2-phenylethyl, 3-phenylpropyl or α,α-dimethylbenzyl. C₇-C₁₂ -aralkyl radicals R², R⁶, R¹⁰ and A can moreover also be, forexample, phenylbutyl or naphthylmethyl. An alkylaralkyl radical A canbe, for example, 4-methylbenzyl, 3-tert.-butylbenzyl,4-methylnaphthyl-1-methylpropyl or 2-(4-isopropylphenyl)-propyl.

C₇ -C₁₀ -alkylphenyl radicals R⁴, R⁵, R⁶, R¹⁰ and R²⁰ can be, forexample, 4-methylphenyl, 4-tert.-butylphenyl, 3-isopropylphenyl or3,5-dimethylphenyl. C₇ -C₁₈ -alkylaryl radicals R¹³ and R²¹ can moreoveralso be, for example, 4-octylphenyl, 4-dodecylphenyl or4-methylnaphth-1-yl.

R⁸ and R⁹ as well as R¹⁹ and R¹⁶, in each case together with the N atomto which they are bonded, can be a heterocyclic ring, for example apyrrolidine, piperidine or morpholine ring.

A can be substituted or interrupted alkyl, for example 2-cyanoethyl,2-ethoxycarbonylethyl, N-butyl-2-carbamoylethyl, 2-methoxyethyl,2-phenoxypropyl, 3-phenylthiopropyl, 2-dodecylthioethyl,2-butylsulfonylethyl, 2-isopropoxypropyl, 2-acetoxybutyl,2-benzoyloxyethyl or 2-(diethylphosphono)-ethyl.

A C₂ -C₁₃ -alkoxymethyl radical R¹¹ can be, for example, methoxymethyl,ethoxymethyl, isopropoxymethyl, butoxymethyl, 2-ethylbutoxymethyl,octyloxymethyl or dodecyloxymethyl.

In the phenolic radical of the formula I, the hydroxyl group can be metaor para to the CH₂ group, but it preferably is in para position. If theCH₂ group is para to the hydroxyl group, R³ is in the meta position. Ifthe CH₂ group is in the meta position, R³ is para to the hydroxyl group.

Preferred stabilisers are compounds of the formula II ##STR7## in whichR² is hydroxyl, C₁ -C₄ -alkyl, C₃ -C₄ -alkenyl, propargyl, benzyl,glycidyl, C₁ -C₄ -alkyl which is substituted by halogen, cyano, --COOR⁷or --CON(R⁸)(R⁹), or a --CO--R¹⁰, --CO--OR⁷, --CO--N(R⁸)(R⁹), --CH₂--CH(R¹¹)--OR¹², --SO--R¹³, --SO₂ --R¹³, --OR⁷ or --OOC--R¹⁰ group, R⁴is C₁ -C₄ -alkyl, R⁵ is hydrogen or C₁ -C₄ -alkyl, R⁶ is hydrogen, C₁-C₁₂ -alkyl, C₃ -C₇ -alkoxyalkyl, cyclohexyl or a group of the formula##STR8## R⁷ is C₁ -C₈ -alkyl, benzyl or cyclohexyl, R⁸ is C₁ -C₈ -alkyl,cyclohexyl or phenyl, R⁹ is hydrogen or C₁ -C₈ -alkyl, or R⁸ and R⁹,together with the N atom, are a piperidine or morpholine ring, R¹⁰ is C₁-C₄ -alkyl, C₂ -C₃ -alkenyl, chloromethyl, phenyl, benzyl or a group ofthe formula ##STR9## R¹¹ is hydrogen, methyl or phenyl, R¹² is hydrogen,C₁ -C₈ -alkyl, --CO--R¹⁰ or --CO--N(R⁸)(R⁹), R¹³ is C₁ -C₄ -alkyl,phenyl or p-tolyl, and A is hydrogen, C₁ -C₈ -alkyl, cyano, allyl orbenzyl.

Particularly preferred stabilisers are compounds of the formula II inwhich R² is hydroxyl, methyl, allyl, benzyl, 2-hydroxyethyl, acetyl,acryloyl, methoxy, acetoxy or a --CO--N(R⁸)(R⁹) group, R⁴ istert.-butyl, R⁵ is methyl or tert.-butyl, R⁶ is hydrogen or C₁ -C₈-alkyl, R⁸ is C₁ -C₈ -alkyl, phenyl or cyclohexyl, R⁹ is hydrogen or C₁-8₈ -alkyl, and A is hydrogen, C₁ -C₈ -alkyl or benzyl.

Some of the compounds of the formula I described herein are known fromGerman Offenlegungsschrift No. 2,647,452, where the compounds aredescribed as optical stabilisers for plastics and where, moreover,various processes are described for preparing these compounds. To theextent that these compounds are new, they can be prepared analogously tothe described compounds.

The synthesis of the compounds preferably starts fromN,N'-bis-(polyalkylpiperid-4-yl)-malonamides of the formula III, whichare reacted with a mole of alkali and a mole of a halogen compound,A--Hal, to give compounds of the formula IV: ##STR10## The phenolicradical can be introduced into the amides IV by reaction with thecorresponding hydroxybenzyl thiocarbamates, hydroxybenzylamines orhydroxybenzyl alkoxides V: ##STR11##

Alternatively, a compound of the formula III can be reacted with a moleof V, and the radical A can be introduced as the second step.

The order of the reaction steps can be altered as desired, and, forexample, a dialkyl malonate can be reacted with A--Hal to give theintermediate A--CH(COOR)₂, which is then reacted either first with acompound of the formula V and then with a 4-aminopiperidine compound ofthe formula VI ##STR12## or vice versa.

The 4-aminopiperidines of the formula VI are known from GermanOffenlegungsschriften Nos. 2,040,975 and 2,349,962, and are prepared byreductive amination of the 4-oxopiperidines.

The radical R² can be introduced at as early a stage as the synthesis ofVI, or after any one of the subsequent synthesis steps.

It can be introduced by the customary methods of N-substitutingsecondary amines, for example by reaction with the correspondinghalogeno compounds Hal--R².

If R² is a --CH₂ --CH(R¹¹)--OR¹² radical, it can be introduced byreacting it with an oxirane, ##STR13## and if desired subsequentlyalkylating or acylating the hydroxyl group. An R² hydroxyl group can beintroduced by reducing the corresponding N-oxyls. Etherification oresterification of the N-hydroxyl compounds gives the compounds in whichR² is an --OR⁷ or --OOC--R¹⁰ group.

Examples of individual compounds of the formula I of the type which,according to the invention, can be used as optical stabilisers forcolour photographic recording material are the following compounds:

    __________________________________________________________________________     ##STR14##                                                                    Com-                                                                          pound                                                                         No. R.sup.5                                                                             A        R.sup.6      R.sup.2                                       __________________________________________________________________________    1   CH.sub.3                                                                            H        n-C.sub.8 H.sub.17                                                                         COCHCH.sub.2                                  2   CH.sub.3                                                                            H        n-C.sub.4 H.sub.9                                                                          CH.sub.3                                      3   CH.sub.3                                                                            H        H            CH.sub.3                                      4   CH.sub.3                                                                            H        C.sub.2 H.sub.5                                                                            COCH.sub.3                                    5   tert.-butyl                                                                         H        H            COCHCH.sub.2                                  6   tert.-butyl                                                                         n-C.sub.4 H.sub.9                                                                      H            COCHCH.sub.2                                  7   tert.-butyl                                                                         H        n-C.sub.4 H.sub.9                                                                          COCH.sub.3                                    8   tert.-butyl                                                                         C.sub.2 H.sub.5                                                                        H            COCHCH.sub.2                                  9   tert.-butyl                                                                         n-C.sub.4 H.sub.9                                                                      H            CH.sub.3                                      10  tert.-butyl                                                                         C.sub.2 H.sub.5                                                                        H            CH.sub.2 CHCH.sub.2                           11  tert.-butyl                                                                         H        n-C.sub.4 H.sub.9                                                                          CH.sub.3                                      12  tert.-butyl                                                                         H        H            COCH.sub.3                                    13  tert.-butyl                                                                         H        n-C.sub.4 H.sub.9                                                                          benzyl                                        14  tert.-butyl                                                                         CH.sub.2 CHCH.sub.2                                                                    H            CH.sub.2 CHCH.sub.2                           15  tert.-butyl                                                                         H        n-C.sub.4 H.sub.9                                                                          COCHCH.sub.2                                  16  tert.-butyl                                                                         benzyl   H            benzyl                                        17  tert.-butyl                                                                         benzyl   CH.sub.2 CH.sub.2 OH                                                                       CH.sub.3                                      18  tert.-butyl                                                                         n-C.sub.4 H.sub.9                                                                      n-C.sub.4 H.sub.9                                                                          COCHCH.sub.2                                  19  tert.-butyl                                                                         n-C.sub.4 H.sub.9                                                                      n-C.sub.4 H.sub.9                                                                          benzyl                                        20  tert.-butyl                                                                         C.sub.2 H.sub.5                                                                        n-C.sub.6 H.sub.13                                                                         CH.sub.2 CHCH.sub.2                           21  tert.-butyl                                                                         n-C.sub.8 H.sub.17                                                                     CH.sub.3     CON(CH.sub.3).sub.2                           22  tert.-butyl                                                                         H        cyclohexyl   CH.sub.2 CH.sub.2 OH                          23  tert.-butyl                                                                         H                                                                                       ##STR15##   COCH.sub.3                                    __________________________________________________________________________     ##STR16##                                                                     ##STR17##                                                                    __________________________________________________________________________

The compounds of the formula I are sparingly soluble in water, and theyare therefore preferably added to the photographic layers in the form ofa dispersion or emulsion. The stabilisers are generally incorporatedinto the photographic material together with the colour couplers. Forthis purpose, the compounds of the formula I are dissolved together withthe colour couplers and if desired with further optical stabilisers in alow-boiling organic solvent, such as methyl acetate, ethyl acetate,carbon tetrachloride, chloroform, methanol, ethanol, n-butanol, dioxane,acetone or benzene, a high-boiling organic solvent, such as tricresylphosphate, N,N-diethyllauramide, di-n-butyl phthalate or ethylN-diphenylcarbamate, or a solvent mixture of the above-mentionedlow-boiling and high-boiling organic solvents, the solution obtained isadded to a protective colloid solution, such as, in particular, anaqueous gelatin solution, and the solution is dispersed therein by meansof a colloid mill or a homogeniser or by using ultrasound.

The dispersions thus obtained are then used for preparing the layers ofrecording materials for colour photography. These layers can be, forexample, intermediate or protective layers, but in particularlight-sensitive (blue-, green- and red-sensitive) silver halide emulsionlayers in which the bluish green (cyan), purple (magenta) and yellowdyes are formed from the corresponding colour couplers as the exposedrecording material is developed.

If desired, the optical stabiliser can also be applied in the treatmentbaths which are used after the color-developing, for example in fixingand/or washing baths, but it is necessary for the compounds of theformula I to have a certain solubility in alcohols (methanol/ethanol),aqueous alkali and/or water. If the diffusion transfer method is used,the stabiliser can also be incorporated into a receiving layer.

The silver halide layers can contain any colour couplers, in particularbluish green, purple and yellow couplers, which are used to form saiddyes and hence the colour images.

In the photographic recording material according to the presentinvention, the stabilisers of the formula I can be combined in the samelayer not only with the colour couplers but in addition also withultraviolet absorbers or other optical stabilisers.

The silver halide emulsions preferably contain, as a binder, gelatin, ifdesired in a mixture with other high molecular weight natural orsynthetic compounds.

The silver halide emulsions can be, for example, silver bromide, silverchloride or silver iodide emulsions or even emulsions which contain amixture of silver halides, for example silver bromide iodide or silverchloride bromide emulsions.

The emulsions can be chemically sensitised, and they can also containcustomary organic stabilisers and antifogging agents and also customaryplasticisers, for example glycerol. The emulsions can also be hardenedby means of the hardening agents customary for gelatin. The emulsionscan also contain customary casting aids. The emulsions can be applied tosupports customary for photographic recording material.

It is possible to use customary developer baths to develop the colourphotographic recording material. These baths generally contain adeveloper substance of the p-phenylenediamine type, a developingretarder, such as potassium bromide, an antioxidant, such as sodiumsulfite or hydroxylamine, and a base, for example an alkali metalhydroxide or alkali metal carbonate. The developing baths can alsocontain customary antifogging agents and complexing agents.

The optical stabilisers to be used according to the invention are, incertain cases, also suitable for protecting colour photographic layersin which the dyes are incorporated directly into the emulsion and theimage is generally by selective bleaching.

The amount of the optical stabiliser(s) can vary within wide limits andis approximately within the range from 1 to 2,000 mg, preferably 100 to800 and in particular 200-500, mg per m² of the layer into which it (orthey) is (or are) incorporated.

If the photographic material contains an agent which absorbs UVradiation, this agent can be present together with the opticalstabiliser in one layer or in an adjacent layer. The weight ratiobetween the ultraviolet absorber and the optical stabiliser of theformula I is about (2-10):1, the molar ratio being about (5-20):1.Examples of ultraviolet absorbers are compounds of the benzophenone,acrylonitrile, thiazolidone, benzotriazole, oxazole, thiazole andimidazole

The colour images obtained by exposing and developing the recordingmaterial according to the invention have very good light fastness tovisible and ultraviolet light. The compounds of the formula I arevirtually colourless, so that the images are not discoloured; they arealso highly compatible with the customary photographic additives presentin the individual layers. Owing to their high effectiveness, it ispossible to reduce their level and thus to avoid their precipitating orcrystallising when they are incorporated in the form of an organicsolution into the aqueous binder emulsions which are used for preparingphotographic layers. The optical stabilisers have no adverse effect onthe individual processing steps necessary for producing the colourimages after the photographic recording material has been exposed.Furthermore the phenomenon of pressure fogging, which can frequentlyarise in the case of blue-sensitive emulsions, can be largelysuppressed. Pressure fogging can arise, for example, when photographicmaterials (silver halide emulsion layers which are present on a supportmade of natural or synthetic materials) are subjected to mechanicalstresses, for example twisting, bending or rubbing, in the course oftheir preparation or in the course of the treatment before thedeveloping (T. H. James, The Theory of Photographic Process 4th Edition,Macmillan, New York, N.Y. 1977, page 23 et seq., page 166 et seq.).

The following example illustrates the present invention in more detailwithout limiting it.

EXAMPLE

0.087 g of the yellow coupler of the formula ##STR18##

and 0.026 g of one of the optical stabilisers given in the followingtables are dissolved in 2.0 ml of a mixture of tricresyl phosphate/ethylacetate (1.5 g in 100 ml). 7.0 ml of a 6% gelatin solution, 0.5 ml of an8% solution of the wetting agent of the formula ##STR19## inisopropanol/water (3:4), and 0.5 ml of water are added to this solutionand are emulsified therein using 100-Watt ultrasound for 5 minutes. 2.5ml of the emulsion thus obtained are admixed with 2.0 ml of a silverbromide emulsion with a silver content of 6.0 g per liter, 0.7 ml of a1% aqueous solution of hardening agent of the formula ##STR20## and 3.8ml of water, and the mixture is brought to pH 6.5 and is cast onto whitesubbed plastic-coated paper stretched over a glass plate.

When the cast material has solidified, it is dried in a drying cabinetat room temperature by means of circulating air.

7 days later, samples cut to a size of 35×180 mm are exposed under astep wedge with 3,000 Lux.s and are then processed in Kodak's Ektaprint2^(R) process.

The yellow wedges thus obtained are irradiated in an AtlasWeather-Ometer by means of a 2,500-W xenon lamp to a total of 42kJoule/cm² (a comparative sample contains no optical stabiliser).

The table shows the percentage decreases in colour density from anoriginal density of 1.0.

    ______________________________________                                        Optical stabiliser                                                                          Colour density Loss in %                                        No.           (reflectance)                                                   ______________________________________                                                      49                                                              1             26                                                              2             32                                                              5             30                                                              7             32                                                              10            30                                                              11            30                                                              ______________________________________                                    

What is claimed is:
 1. A recording material for colour photographywhich, in at least one light-sensitive silver halide emulsion layer, anintermediate layer, an image-receiving layer and/or a protective layer,contains, as a stabiliser, at least one polyalkylpiperidine compound ofthe formula I ##STR21## in which R¹ is hydrogen or methyl, R² ishydroxyl, C₁ -C₁₂ -alkyl, C₃ -C₆ -alkenyl, C₃ -C₄ -alkynyl, C₇ -C₁₂-aralkyl, gycidyl, C₁ -C₄ -alkyl which is substituted by halogen, cyano,--COOR⁷ or --CON(R⁸)(R⁹), or a --CO--R¹⁰, --CO--OR⁷, --CO--N--(R⁸)(R⁹),--CH₂ --CH(R¹¹)--OR¹², --SO--R¹³, --SO₂ --R¹³, --OR⁷ or --OOC--R¹⁰group, R³ is hydrogen or methyl, R⁴ is C₁ -C₈ -alkyl, C₅ -C₈-cycloalkyl, C₇ -C⁹ -phenylalkyl, phenyl or C₇ -C₁₀ -alkylphenyl, R⁵ ishydrogen, C₁ -C₈ -alkyl, C₅ -C₈ -cycloalkyl, C₇ -C₉ -phenylalkyl, phenylor C₇ -C₁₀ -alkylphenyl, R⁶ is hydrogen, C₁ -C₁₈ -alkyl, C.sub. 3 -C₆-alkenyl, C₃ -C₁₂ -cycloalkyl, C₇ -C₁₂ -aralkyl, C₇ -C₁₀ -alkylphenyl orC₂ -C₄ alkyl which is substituted by --OR⁸, --N(R⁹)₂ or a group of theformula ##STR22## R⁷ is C₁ -C₁₂ -alkyl, allyl, cyclohexyl or benzyl, R⁸is C₁ -C₁₂ -alkyl, allkyl, cyclohexyl, benzyl or phenyl, R⁹ is hydrogen,C₁ -C₁₂ -alkyl, allyl, cyclohexyl or benzyl, or R⁸ and R⁹, together withthe N atom to which they are bonded, are a 5-or 6-membered heterocyclicring, R¹⁰ is hydrogen, C₁ -C₁₂ -alkyl, C₂ -C₆ -alkenyl, chloromethyl, C₅-C₈ -cycloalkyl, C₇ -C₁₂ -aralkyl, phenyl, C₇ -C₁₀ -alkylphenyl orphenyl, phenylmethyl or phenylethyl which are substituted by 1 or 2 C₁-C₄ -alkyl groups and a hydroxyl group, R¹¹ is hydrogen, C₁ -C₄ -alkyl,C₂ -C₁₃ -alkoxymethyl, phenyl or phenoxymethyl, R¹² is hydrogen, C₁ -C₁₂-alkyl, --CO--R¹⁰ or --CO--N(R⁸)(R⁹), R¹³ is C₁ -C₁₂ -alkyl, phenyl orC₇ -C₁₈ -alkylaryl, A is hydrogen, C₁ -C₁₈ -alkyl, C₁ -C₁₀ -alkyl whichis substituted by at least one of the --OR¹⁴, --SR¹⁵, --CN,--CO--X--R¹⁶, --O--CO--R¹⁷ or --P(O)(OR¹⁸)₂ groups, C₂ -C₂₀ -alkyl whichis interrupted by --O--, --S--, --SO-- or --SO₂ --, C₃ -C₁₈ -alkenyl, C₃-C₈ -alkynyl, C₃ -C₁₂ -cycloalkyl, C₆ -C₁₀ -alkylcycloalkyl, C₆ -C₁₀-cycloalkylalkyl, C₇ -C₁₂ -aralkyl, C₈ -C₁₆ -alkylaralkyl, phenyl, a--CN, --CO-- R²⁰, --SO₂ R²¹ or --P(O)(OR¹⁸) group or one of thefollowing groups. ##STR23## in which X is --O-- or --N(R¹⁹)--, R¹⁴ isphenyl, benzyl or cyclohexyl, R¹⁵ is phenyl or C₇ -C₉ -phenylalkyl, R¹⁶is C₁ -C₁₈ -alkyl, C₅ -C₈ -cycloalkyl and R¹⁷ is C₁ -C₁₈ -alkyl, C₅ -C₈-cycloalkyl, phenyl, C₇ -C₉ -phenylalkyl or a group of the formula##STR24## R¹⁸ is C₁ -C₈ -alkyl, allyl or phenyl, R¹⁹ is hydrogen, C₁-C₁₈ -alkyl, allkyl, cyclohexyl, benzyl or phenyl or, together with R¹⁶and the N atom, a 5- or 6-membered heterocyclic ring, R²⁰ is hydrogen,C₁ -C₁₈ -alkyl, C₂ -C₆ -alkenyl, C₅ -C₈ -cycloalkyl, phenyl, C₇ -C₁₀-alkylphenyl or C₇ -C₉ -phenylalkyl, R²¹ is C₁ -C₁₈ -alkyl, cyclohexyl,phenyl, naphthyl, C₇ -C₁₈ -alkylaryl, C₇ -C₉ -phenylalkyl or a group ofthe formula ##STR25## m is zero, 1 or 2, and n is zero, 1, 2 or
 3. 2. Arecording material for colour photography according to claim 1, whereinthe stabiliser is a compound of the formula II ##STR26## in which R² ishydroxyl, C₁ -C₄ -alkyl, C₃ -C₄ -alkenyl, propargyl, benzyl, glycidyl,C₁ -C₄ -alkyl which is substituted by halogen, cyano, --COOR⁷ or--CON(R⁸)(R⁹), or a --CO--R¹⁰, --CO--OR⁷, --CO--N(R⁸)(R⁹), --CH₂--CH(R¹¹)--OR¹², --SO--R¹³, --SO₂ --R¹³, --OR⁷ or --OOC--R¹⁰ group, R⁴is C₁ -C₁₄ -alkyl, R⁵ is hydrogen or C₁ -C₄ -alkyl, R⁶ is hydrogen, C₁-C₁₂ -alkyl, C₃ -C₇ -alkoxyalkyl, cyclohexyl or a group of the formula##STR27## R⁷ is C₁ -C₈ -alkyl, benzyl or cyclohexyl, R⁸ is C₁ -C₈-alkyl, cyclohexyl or phenyl, R⁹ is hydrogen or C₁ -C₈ alkyl, or R⁸ andR⁹, together with the N atom, are a piperidine or morpholine ring, R¹⁰is C₁ -C₄ -alkyl, C₂ -C₃ -alkenyl, chloromethyl, phenyl, benzyl or agroup of the formula ##STR28## R¹¹ is hydrogen, methyl or phenyl, R¹² ishydrogen, C₁ -C₈ -alkyl, --CO--R¹⁰ or --CO--N(R⁸)(R⁹), R¹³ is C₁ -C₄-alkyl, phenyl or p-tolyl, and A is hydrogen, C₁ -C₈ -alkyl, cyano,allyl or benzyl.
 3. A recording material for colour photographyaccording to claim 2, wherein the stabiliser is a compound of theformula II in which R² is hydroxyl, methyl, allyl, benzyl,2-hydroxyethyl, acetyl, acrylolyl, methoxy, acetoxy or a --CO--N(R⁸)(R⁹) group, R⁴ is tert.-butyl, R⁵ is methyl or tert.-butyl, R⁶ ishydrogen or C₁ -C₈ -alkyl, R⁸ is C₁ -C₈ -alkyl, phenyl or cyclohexyl, R⁹is hydrogen or C₁ -C₈ alkyl, and A is hydrogen, C₁ -C₈ -alkyl or benzyl.4. A recording material for colour photography according to claim 1,which contains, in addition to a stabiliser of the formula I, an opticalstabiliser of the ultraviolet absorber class.
 5. A recording materialfor colour photography according to claim 1, which contains 1 to 2,000mg of compound of the formula I per m².